Does Light Curve Spacetime?

[trees and plants]

Hello there.The question is as stated:does light curve spacetime?We know that bodies with mass do curve spacetime but does a massless particle or wave like light curve spacetime?Thank you.

 

[anuttarasammyak]

Yes. EM field has energy momentum tensor which is a part of RHS of Einstein equation.

 

[trees and plants]

Is there any physical body in the universe without energy?

 

[Ibix]

We know that bodies with mass do curve spacetime but does a massless particle or wave like light curve spacetime?

In principle. The energy densities needed to test it are impossible to achieve.

Is there any physical body in the universe without energy?

No.

 

[trees and plants]

In principle. The energy densities needed to test it are impossible to achieve.

No.

How do you know it is correct?Every massless physical body has energy?If it did not have what would happen?

 

[Ibix]

What do you think "without energy" would mean, physically?

 

[trees and plants]

What do you think "without energy" would mean, physically?

I think that we cannot observe things that do not have energy or experiment with them.But the question just came to my mind perhaps it is wrong.

 

[Dale]

Every massless physical body has energy?If it did not have what would happen?

If a massless body did not have energy then it would also not have momentum. I am not sure in what sense you could say that it even exists.

Anyway that is rather off topic from your OP.

 

[vanhees71]

To put it differently: To observe something it must interact with some meausurement device or directly with your body to perceive some signal with your senses, but this means it must exchange energy with the measurement device, and if it has no energy there's nothing it can exchange and thus it simply doesn't exist.

Electromagnetic waves, and light is nothing else than an electromagnetic wave with frequencies we can sense with our eyes, of course carry energy, momentum, and angular momentum and thus it can interact with measurement devices or our retina to sense it.

Now the Einstein field equations basically say that the sources of the gravitational field (described by the Einstein Tensor related to the curvature of spacetime) are all kinds of energy, momentum, and stress (described by the corresponding gauge-invariant symmetric energy-momentum tensor of the corresponding fields), and this implies that also electromagnetic waves are contributing to these sources and thus cause a gravitational field.

 

[robphy]

possibly interesting:
https://projecteuclid.org/download/pdf_1/euclid.cmp/1103841572
Commun. math. Phys. 13, 163—174 (1969)
The Gravitational Field of Light
W. B. Bonnor

 

[anuttarasammyak]

No.

How we should understand physical quantity but has nothing to do with energy ,e.g. entropy and distribution function in statistical mechanics, wave function or probability amplitude in QM. I suppose they are not physical body neither have energy. We shall call them "physical information" ?

 

[Ibix]

entropy and distribution function in statistical mechanics,

I would say that these are properties of a physical system, just as energy is.

wave function or probability amplitude in QM

You might argue that the wave function is the physical body, to the extent that makes sense in quantum physics. Energy is the corresponding eigenvalue, anyway.